This invention relates to telecommunications apparatus for enabling a fixed telecommunication system, adapted for use with a public switched telephone network (PSTN), to operate over a radio telecommunications network. The term xe2x80x9cfixed systemxe2x80x9d as used herein is intended to mean a local system via which a number of communication devices (e.g. telephones, facsimile machines, data devices) normally communicate. The communication devices themselves may be cordless and/or mobile and operate within the area local to the fixed system. The system is fixed from the subscriber""s point of view.
In telecommunications, the final drop from the local telephone exchange to a subscriber""s terminal or private exchange is known as the xe2x80x9clocal loopxe2x80x9d. Traditionally this comprised a network of copper-pair lines, which are expensive to install and to maintain. In densely populated areas and/or countries with low telephone penetration this approach is impracticable. Wireless Local Loop (WLL) is a modern alternative to the copper network. In WLL a wireless (for example radio or infrared) system makes up all or part of the transmission path between the subscriber and the local exchange.
WLL allows the flexible allocation and reallocation of network resources and also has reduced installation time compared with fixed line networks. Thus WLL is particularly suitable for: providing network services quickly to small businesses and residential customers; cutting the cost of the local loop in remote or rural areas; providing telephone services in areas where accelerated development is required by regulatory bodies; and flexibly providing telecommunications services for instance at temporary locations such as exhibitions etc.
WLL typically use microwave, cordless or cellular technologies. In contrast to mobile telecommunications, fixed wireless terminals (or WLL terminals) are fixed and do not act as mobile terminals.
Generally such fixed wireless terminals (such as WLL terminals) comprise a transceiver, an external power supply and an antenna. More particularly a terminal comprises an RF section for receiving and transmitting RF signals via an antenna; an interface for connecting a subscriber device to the wireless local loop terminal; a baseband section for converting received RF signals into baseband signals for transmission to the subscriber device and converting received baseband signals into RF signals for transmission by the RF section; and a subscriber line interface circuit for providing network dependent characteristics e.g. the tones (ringing, dial, engaged (busy) etc.) which, in a fixed network, are conventionally provided by the local exchange. In the context of this specification, ringing tone means the sound a user hears when a device is ringing another number. A ringing generator of the subscriber line interface circuit activates the sound produced by the device to alert a user that an incoming call is being received (commonly referred to as a ring tone). Such a terminal is capable of supporting many forms of transmission, for example speech, fax or data, and has interfaces for connecting to appropriate devices. An example of a known WLL system is described in British Patent Application no. 2311696.
The WLL terminals are fixed terminals i.e. they are not designed to be mobile within the network. The terminals are fixed to the walls in a user""s premises, within a cab of a user""s lorry, boat etc. or to the walls of buildings for public network coverage. The terminals are usable with a subscriber""s device such as a telephone (mobile or otherwise) or a fax machine. An installer or service provider may interact with the terminal via a service handset to find the best place to locate the terminal, make test calls or monitor terminal and radio network parameters.
In known fixed wireless terminals the configuration of the terminal is set at the factory. That is to say that the network characteristics to be used are set at the point of manufacture. A terminal is thus configured in accordance with the intended market. This is undesirable since stockpiling of one type and shortages of another type may occur.
In accordance with the invention there is provided a wireless terminal comprising memory for storing characteristics for at least one network, means for accepting network information particular to a subscriber, and processing means for reading the subscriber network information and, on the basis of the subscriber network information, selecting appropriate network characteristics for subsequent use by the terminal.
A manufacturer may therefore make a surplus of fixed wireless terminals, each of which is programmed with the network characteristics of the major markets of the manufacturer. The terminal automatically reads the subscriber""s information and configures itself in accordance with the subscriber information.
Preferably the terminal also comprises means for accepting a subscriber information memory module having stored thereon the network information particular to the subscriber. Alternatively the terminal may include programmable memory for storing the network information particular to the subscriber. The network information particular to the subscriber may be downloaded via a network or from a subscriber""s device.
The processing means may be arranged to configure a subscriber line interface circuit in accordance with the selected appropriate network characteristics.
The terminal may further include an immobilising circuit that immobilises the terminal on detection of tampering with the terminal. Preferably the terminal is arranged to read the network information particular to the subscriber when the immobilser circuit is activated and to prohibit changes to the network characteristics unless the immobiliser circuit is re-initialised by an authorised person.
Preferably the subscriber network information relates to the country in which the subscriber is registered for the provision of mobile services and/or the network operator with whom the subscriber is registered. The stored network characteristics preferably include country and/or network operator details as well as tone sequence information, details of emergency numbers, hook detection times, pulse/TDMF dialling information etc.
The terminal may be arranged to operate according to a required standard e.g. the GSM standard or CDMA. In the case of GSM, preferably the processor is arranged to read at least the mobile country code of the subscriber network information. The processor may also be arranged to read the mobile network code of the subscriber network information.
In accordance with a further aspect of the invention, in a method of configuring a wireless terminal, the method comprises: reading network information particular to a subscriber, comparing said network information with stored information relating to characteristics for at least one network, selecting, on the basis of the subscriber network information, appropriate network characteristics for subsequent use by the terminal; and configuring the terminal in accordance with the selected network characteristics.
A further aspect of the invention relates to apparatus for enabling a telephone system, adapted for use with a public switched telephone network, to operate over a radio telecommunications network, the apparatus comprising a connector for connecting a subscriber device to the apparatus; an antenna for coupling the apparatus to the radio telecommunications network; and a subscriber line interface device including signal generating means for generating a signal to produce a dialling tone on a subscriber device and for generating a signal to cause ringing of the subscriber device on receipt of an incoming call signal from the radio telecommunications system; signal converting means for converting a dialling signal generated by a subscriber device into a code signal for accessing the radio telecommunications network; and detector means for detecting when a subscriber device has been activated to answer an incoming call or making an outgoing call; and control means for reading network information specific to a subscriber and configuring the subscriber line interface device accordingly.
Preferably the apparatus also stores information relating to characteristics for at least one network, and the control means is arranged to compare said subscriber network information with the characteristics for at least one network and to select, on the basis of the subscriber network information, appropriate network characteristics for subsequent use by the apparatus.
In a yet further aspect of the invention, there is provided a method of configuring apparatus for enabling a fixed telephone system, adapted for use with a public switched telephone network, to operate over a radio telecommunications network, the method comprising reading network information particular to a subscriber and configuring network characteristics of the apparatus on the basis of the subscriber network information.